The present technology relates to a touch detector, and more specifically relates to a touch detector detecting a touch based on a change in capacitance by an external adjacent object and a method of driving the same, a display with a touch detection function and an electronic unit including such a touch detector.
In recent years, attention has been given to a display capable of inputting information by a button image instead of a typical mechanical button by being provided with a contact detection device, that is, a so-called touch panel mounted on or integrated with a display such as a liquid crystal display and displaying various button images on the display. As a display including such a touch panel does not need an input device such as a keyboard, a mouse or a keypad, there is a tendency to expand the use of such a display to portable information terminals such as cellular phones in addition to computers.
Systems of touch detectors include an optical system, a resistance system and the like, but expectations are placed on a capacitance system touch detector which has a relatively simple configuration and is allowed to achieve low power consumption. For example, Japanese Unexamined Patent Application Publication No. 2009-244958 proposes a display in which a common electrode for display originally included in a display also serves as one (a drive electrode) of a pair of electrodes for touch sensor and the other (a touch detection electrode) is arranged to intersect the common electrode. A capacitance is formed between the drive electrode and the touch detection electrode, and the capacitance is changed by an external adjacent object. This display analyzes a touch detection signal obtained from the touch detection electrode when a drive signal is applied to the drive electrode to detect the external adjacent object with use of the change in the capacitance. In this display, while the drive signal is sequentially applied to the common electrode (drive electrode) to perform line-sequential scanning, thereby performing a display operation, the touch detection signal obtained from the touch detection electrode in response to the drive signal is analyzed to perform a touch detection operation.